Thanks Charles for your time
The car depicted in the video you posted is not the same as my 2019 Macan S & has a different PCM, mine is below.
The back button seemingly works on all PCM modes including CarPlay

3EC48307-3F1D-40B6-9F1C-B38021C4F630.jpeg

So if you press the white circle on the right hand side (if your picture was the right way up), do you get back to the home screen which is currently displayed? If you are in a CarPlay app and you want to get back to the home screen, it's this white circle that you should press.

Charles, I do not wish to be ungracious, given that it seems you are genuinely trying to help, but in my very first post I explained what did & did not work / happen. So no the white home button shaped icon that you identified at the bottom right does sweet FA unless it’s pressed for 2 seconds or so when Siri will appear & try to connect me with the Prime Minister or find somewhere that I could get my dogs fleas attended to.

Thanks Guy
I got half way there with help from a chap on another Forum & set up a virtual home button, but didn’t realise it was capable of being configured in several ways. So I’ll try it as you’ve suggested.